人脸生成(Face Generation)

在该项目中,你将使用生成式对抗网络(Generative Adversarial Nets)来生成新的人脸图像。

获取数据

该项目将使用以下数据集:

  • MNIST
  • CelebA

由于 CelebA 数据集比较复杂,而且这是你第一次使用 GANs。我们想让你先在 MNIST 数据集上测试你的 GANs 模型,以让你更快的评估所建立模型的性能。

如果你在使用 FloydHub, 请将 data_dir 设置为 "/input" 并使用 FloydHub data ID "R5KrjnANiKVhLWAkpXhNBe".

In [1]:
data_dir = './data'

# FloydHub - Use with data ID "R5KrjnANiKVhLWAkpXhNBe"
#data_dir = '/input'


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
import helper

helper.download_extract('mnist', data_dir)
helper.download_extract('celeba', data_dir)
Downloading mnist: 9.92MB [00:00, 35.0MB/s]                            
Extracting mnist: 100%|██████████| 60.0k/60.0k [00:10<00:00, 5.80kFile/s]
Downloading celeba: 1.44GB [03:29, 6.90MB/s]                               
Extracting celeba...

探索数据(Explore the Data)

MNIST

MNIST 是一个手写数字的图像数据集。你可以更改 show_n_images 探索此数据集。

In [2]:
show_n_images = 25

"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
%matplotlib inline
import os
from glob import glob
from matplotlib import pyplot

mnist_images = helper.get_batch(glob(os.path.join(data_dir, 'mnist/*.jpg'))[:show_n_images], 28, 28, 'L')
pyplot.imshow(helper.images_square_grid(mnist_images, 'L'), cmap='gray')
/home/ubuntu/anaconda3/envs/tensorflow_p36/lib/python3.6/site-packages/matplotlib/font_manager.py:278: UserWarning: Matplotlib is building the font cache using fc-list. This may take a moment.
  'Matplotlib is building the font cache using fc-list. '
Out[2]:
<matplotlib.image.AxesImage at 0x7f9be86fda58>

CelebA

CelebFaces Attributes Dataset (CelebA) 是一个包含 20 多万张名人图片及相关图片说明的数据集。你将用此数据集生成人脸,不会用不到相关说明。你可以更改 show_n_images 探索此数据集。

In [3]:
show_n_images = 25

"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
mnist_images = helper.get_batch(glob(os.path.join(data_dir, 'img_align_celeba/*.jpg'))[:show_n_images], 28, 28, 'RGB')
pyplot.imshow(helper.images_square_grid(mnist_images, 'RGB'))
Out[3]:
<matplotlib.image.AxesImage at 0x7f9c16cfffd0>

预处理数据(Preprocess the Data)

由于该项目的重点是建立 GANs 模型,我们将为你预处理数据。

经过数据预处理,MNIST 和 CelebA 数据集的值在 28×28 维度图像的 [-0.5, 0.5] 范围内。CelebA 数据集中的图像裁剪了非脸部的图像部分,然后调整到 28x28 维度。

MNIST 数据集中的图像是单通道的黑白图像,CelebA 数据集中的图像是 三通道的 RGB 彩色图像

建立神经网络(Build the Neural Network)

你将通过部署以下函数来建立 GANs 的主要组成部分:

  • model_inputs
  • discriminator
  • generator
  • model_loss
  • model_opt
  • train

检查 TensorFlow 版本并获取 GPU 型号

检查你是否使用正确的 TensorFlow 版本,并获取 GPU 型号

In [4]:
"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
from distutils.version import LooseVersion
import warnings
import tensorflow as tf

# Check TensorFlow Version
assert LooseVersion(tf.__version__) >= LooseVersion('1.0'), 'Please use TensorFlow version 1.0 or newer.  You are using {}'.format(tf.__version__)
print('TensorFlow Version: {}'.format(tf.__version__))

# Check for a GPU
if not tf.test.gpu_device_name():
    warnings.warn('No GPU found. Please use a GPU to train your neural network.')
else:
    print('Default GPU Device: {}'.format(tf.test.gpu_device_name()))
TensorFlow Version: 1.10.0
Default GPU Device: /device:GPU:0

输入(Input)

部署 model_inputs 函数以创建用于神经网络的 占位符 (TF Placeholders)。请创建以下占位符:

  • 输入图像占位符: 使用 image_widthimage_heightimage_channels 设置为 rank 4。
  • 输入 Z 占位符: 设置为 rank 2,并命名为 z_dim
  • 学习速率占位符: 设置为 rank 0。

返回占位符元组的形状为 (tensor of real input images, tensor of z data, learning rate)。

In [5]:
import problem_unittests as tests

def model_inputs(image_width, image_height, image_channels, z_dim):
    """
    Create the model inputs
    :param image_width: The input image width
    :param image_height: The input image height
    :param image_channels: The number of image channels
    :param z_dim: The dimension of Z
    :return: Tuple of (tensor of real input images, tensor of z data, learning rate)
    """
    # TODO: Implement Function
    input_real = tf.placeholder(tf.float32, [None, image_width, image_height, image_channels], name='tensor_iamges') 
    input_z = tf.placeholder(tf.float32, [None, z_dim], name='tensor_z')
    learning_rate = tf.placeholder(tf.float32, name='learning_rate')

    return input_real, input_z, learning_rate


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_model_inputs(model_inputs)
Tests Passed

辨别器(Discriminator)

部署 discriminator 函数创建辨别器神经网络以辨别 images。该函数应能够重复使用神经网络中的各种变量。 在 tf.variable_scope 中使用 "discriminator" 的变量空间名来重复使用该函数中的变量。

该函数应返回形如 (tensor output of the discriminator, tensor logits of the discriminator) 的元组。

In [6]:
def discriminator(images, reuse=False, alpha=0.2):
    """
    Create the discriminator network
    :param image: Tensor of input image(s)
    :param reuse: Boolean if the weights should be reused
    :return: Tuple of (tensor output of the discriminator, tensor logits of the discriminator)
    """
    # TODO: Implement Function
    with tf.variable_scope('discriminator', reuse=reuse):
        # Input layer is 28x28x3
        x1 = tf.layers.conv2d(images, 128, 5, strides=2, padding='same', kernel_initializer = tf.contrib.layers.xavier_initializer())
        relu1 = tf.nn.dropout(tf.maximum(alpha * x1, x1), 0.8)
        # 14x14x128
        
        x2 = tf.layers.conv2d(relu1, 256, 5, strides=2, padding='same', kernel_initializer = tf.contrib.layers.xavier_initializer())
        bn2 = tf.layers.batch_normalization(x2, training=True)
        relu2 = tf.nn.dropout(tf.maximum(alpha * bn2, bn2), 0.8)
        # 7x7x256

        # Flatten it
        flat = tf.reshape(relu2, (-1, 7*7*256))
        logits = tf.layers.dense(flat, 1)
        out = tf.sigmoid(logits)
        
        return out, logits


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_discriminator(discriminator, tf)
Tests Passed

生成器(Generator)

部署 generator 函数以使用 z 生成图像。该函数应能够重复使用神经网络中的各种变量。 在 tf.variable_scope 中使用 "generator" 的变量空间名来重复使用该函数中的变量。

该函数应返回所生成的 28 x 28 x out_channel_dim 维度图像。

In [7]:
def generator(z, out_channel_dim, is_train=True, alpha=0.2):
    """
    Create the generator network
    :param z: Input z
    :param out_channel_dim: The number of channels in the output image
    :param is_train: Boolean if generator is being used for training
    :return: The tensor output of the generator
    """
    # TODO: Implement Function
    with tf.variable_scope('generator', reuse = not is_train):
        # First fully connected layer
        x1 = tf.layers.dense(z, 7*7*256, kernel_initializer = tf.contrib.layers.xavier_initializer())
        # Reshape it to start the convolutional stack
        x1 = tf.reshape(x1, (-1, 7, 7, 256))
        x1 = tf.layers.batch_normalization(x1, training=is_train)
        x1 = tf.maximum(alpha * x1, x1)
        # 7x7x512 now
        
        x2 = tf.layers.conv2d_transpose(x1, 128, 5, strides=2, padding='same', kernel_initializer = tf.contrib.layers.xavier_initializer())
        x2 = tf.layers.batch_normalization(x2, training=is_train)
        x2 = tf.maximum(alpha* x2, x2)
        # 14x14x128 now
        
        # Output layer
        logits = tf.layers.conv2d_transpose(x2, out_channel_dim, 5, strides=2, padding='same')
        # 28x28x3 now
        
        out = tf.tanh(logits)
        
        return out


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_generator(generator, tf)
Tests Passed

损失函数(Loss)

部署 model_loss 函数训练并计算 GANs 的损失。该函数应返回形如 (discriminator loss, generator loss) 的元组。

使用你已实现的函数:

  • discriminator(images, reuse=False)
  • generator(z, out_channel_dim, is_train=True)
In [8]:
def model_loss(input_real, input_z, out_channel_dim):
    """
    Get the loss for the discriminator and generator
    :param input_real: Images from the real dataset
    :param input_z: Z input
    :param out_channel_dim: The number of channels in the output image
    :return: A tuple of (discriminator loss, generator loss)
    """
    # TODO: Implement Function
    g_model = generator(input_z, out_channel_dim)
    d_model_real, d_logits_real = discriminator(input_real)
    d_model_fake, d_logits_fake = discriminator(g_model, reuse=True)

    d_loss_real = tf.reduce_mean(
        tf.nn.sigmoid_cross_entropy_with_logits(logits=d_logits_real, labels=tf.ones_like(d_model_real))*0.9)
    d_loss_fake = tf.reduce_mean(
        tf.nn.sigmoid_cross_entropy_with_logits(logits=d_logits_fake, labels=tf.zeros_like(d_model_fake))*0.9)
    g_loss = tf.reduce_mean(
        tf.nn.sigmoid_cross_entropy_with_logits(logits=d_logits_fake, labels=tf.ones_like(d_model_fake))*0.9)

    d_loss = d_loss_real + d_loss_fake

    return d_loss, g_loss


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_model_loss(model_loss)
Tests Passed

优化(Optimization)

部署 model_opt 函数实现对 GANs 的优化。使用 tf.trainable_variables 获取可训练的所有变量。通过变量空间名 discriminatorgenerator 来过滤变量。该函数应返回形如 (discriminator training operation, generator training operation) 的元组。

In [9]:
def model_opt(d_loss, g_loss, learning_rate, beta1):
    """
    Get optimization operations
    :param d_loss: Discriminator loss Tensor
    :param g_loss: Generator loss Tensor
    :param learning_rate: Learning Rate Placeholder
    :param beta1: The exponential decay rate for the 1st moment in the optimizer
    :return: A tuple of (discriminator training operation, generator training operation)
    """
    # TODO: Implement Function
    t_vars = tf.trainable_variables()
    d_vars = [var for var in t_vars if var.name.startswith('discriminator')]
    g_vars = [var for var in t_vars if var.name.startswith('generator')]

    # Optimize
    with tf.control_dependencies(tf.get_collection(tf.GraphKeys.UPDATE_OPS)):
        d_train_opt = tf.train.AdamOptimizer(learning_rate, beta1=beta1).minimize(d_loss, var_list=d_vars)
        g_train_opt = tf.train.AdamOptimizer(learning_rate, beta1=beta1).minimize(g_loss, var_list=g_vars)

    return d_train_opt, g_train_opt


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_model_opt(model_opt, tf)
Tests Passed

训练神经网络(Neural Network Training)

输出显示

使用该函数可以显示生成器 (Generator) 在训练过程中的当前输出,这会帮你评估 GANs 模型的训练程度。

In [10]:
"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
import numpy as np

def show_generator_output(sess, n_images, input_z, out_channel_dim, image_mode):
    """
    Show example output for the generator
    :param sess: TensorFlow session
    :param n_images: Number of Images to display
    :param input_z: Input Z Tensor
    :param out_channel_dim: The number of channels in the output image
    :param image_mode: The mode to use for images ("RGB" or "L")
    """
    cmap = None if image_mode == 'RGB' else 'gray'
    z_dim = input_z.get_shape().as_list()[-1]
    example_z = np.random.uniform(-1, 1, size=[n_images, z_dim])

    samples = sess.run(
        generator(input_z, out_channel_dim, False),
        feed_dict={input_z: example_z})

    images_grid = helper.images_square_grid(samples, image_mode)
    pyplot.imshow(images_grid, cmap=cmap)
    pyplot.show()

训练

部署 train 函数以建立并训练 GANs 模型。记得使用以下你已完成的函数:

  • model_inputs(image_width, image_height, image_channels, z_dim)
  • model_loss(input_real, input_z, out_channel_dim)
  • model_opt(d_loss, g_loss, learning_rate, beta1)

使用 show_generator_output 函数显示 generator 在训练过程中的输出。

注意:在每个批次 (batch) 中运行 show_generator_output 函数会显著增加训练时间与该 notebook 的体积。推荐每 100 批次输出一次 generator 的输出。

In [11]:
import numpy as np

def train(epoch_count, batch_size, z_dim, learning_rate, beta1, get_batches, data_shape, data_image_mode):
    """
    Train the GAN
    :param epoch_count: Number of epochs
    :param batch_size: Batch Size
    :param z_dim: Z dimension
    :param learning_rate: Learning Rate
    :param beta1: The exponential decay rate for the 1st moment in the optimizer
    :param get_batches: Function to get batches
    :param data_shape: Shape of the data
    :param data_image_mode: The image mode to use for images ("RGB" or "L")
    """
    # TODO: Build Model
    _, image_width, image_height, image_channels = data_shape
    input_real, input_z, learning_rate = model_inputs(image_width, image_height, image_channels, z_dim)
    
    # Calculate losses
    d_loss, g_loss = model_loss(input_real, input_z, image_channels)
    d_train_opt, g_train_opt = model_opt(d_loss, g_loss, learning_rate, beta1)
    
    steps = 0
    
    with tf.Session() as sess:
        sess.run(tf.global_variables_initializer())
        for epoch_i in range(epoch_count):
            for batch_images in get_batches(batch_size):
                # TODO: Train Model
                steps +=1
                batch_images = batch_images*2
                
                # Sample random noise for G
                batch_z = np.random.uniform(-1, 1, size=(batch_size, z_dim))

                # Run optimizers
                _ = sess.run(d_train_opt, feed_dict={input_real: batch_images, input_z: batch_z, learning_rate:0.001})
                _ = sess.run(g_train_opt, feed_dict={input_real: batch_images,input_z: batch_z,learning_rate:0.001})
                if steps % 100 == 0:                    
                    # At the end of each epoch, get the losses and print them out                    
                    train_loss_d = d_loss.eval({input_z: batch_z, input_real: batch_images})                    
                    train_loss_g = g_loss.eval({input_z: batch_z})                    
                    print("Epoch {}/{}...".format(epoch_i+1, epoch_count),                          
                          "Discriminator Loss: {:.4f}...".format(train_loss_d),                          
                          "Generator Loss: {:.4f}".format(train_loss_g))                    
                    show_generator_output(sess, 25, input_z, image_channels, data_image_mode)        

MNIST

在 MNIST 上测试你的 GANs 模型。经过 2 次迭代,GANs 应该能够生成类似手写数字的图像。确保生成器 (generator) 低于辨别器 (discriminator) 的损失,或接近 0。

In [12]:
batch_size = 64
z_dim = 100
learning_rate = 0.0002
beta1 = 0.5


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
epochs = 2

mnist_dataset = helper.Dataset('mnist', glob(os.path.join(data_dir, 'mnist/*.jpg')))
with tf.Graph().as_default():
    train(epochs, batch_size, z_dim, learning_rate, beta1, mnist_dataset.get_batches,
          mnist_dataset.shape, mnist_dataset.image_mode)
Epoch 1/2... Discriminator Loss: 1.0713... Generator Loss: 1.2580
Epoch 1/2... Discriminator Loss: 0.8253... Generator Loss: 1.1224
Epoch 1/2... Discriminator Loss: 1.2169... Generator Loss: 1.2680
Epoch 1/2... Discriminator Loss: 0.9970... Generator Loss: 0.7708
Epoch 1/2... Discriminator Loss: 0.8040... Generator Loss: 0.9048
Epoch 1/2... Discriminator Loss: 0.9043... Generator Loss: 1.1212
Epoch 1/2... Discriminator Loss: 0.9777... Generator Loss: 0.6559
Epoch 1/2... Discriminator Loss: 1.2074... Generator Loss: 0.4944
Epoch 1/2... Discriminator Loss: 1.0567... Generator Loss: 0.6820
Epoch 2/2... Discriminator Loss: 1.2997... Generator Loss: 1.1857
Epoch 2/2... Discriminator Loss: 1.3675... Generator Loss: 0.4254
Epoch 2/2... Discriminator Loss: 0.9415... Generator Loss: 0.6366
Epoch 2/2... Discriminator Loss: 1.2458... Generator Loss: 0.3974
Epoch 2/2... Discriminator Loss: 1.0131... Generator Loss: 1.1332
Epoch 2/2... Discriminator Loss: 1.0461... Generator Loss: 0.7611
Epoch 2/2... Discriminator Loss: 1.1304... Generator Loss: 0.6229
Epoch 2/2... Discriminator Loss: 1.1860... Generator Loss: 0.5524
Epoch 2/2... Discriminator Loss: 0.9402... Generator Loss: 1.3433

CelebA

在 CelebA 上运行你的 GANs 模型。在一般的GPU上运行每次迭代大约需要 20 分钟。你可以运行整个迭代,或者当 GANs 开始产生真实人脸图像时停止它。

In [13]:
batch_size = 32
z_dim = 100
learning_rate = 0.0002
beta1 = 0.5


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
epochs = 1

celeba_dataset = helper.Dataset('celeba', glob(os.path.join(data_dir, 'img_align_celeba/*.jpg')))
with tf.Graph().as_default():
    train(epochs, batch_size, z_dim, learning_rate, beta1, celeba_dataset.get_batches,
          celeba_dataset.shape, celeba_dataset.image_mode)
Epoch 1/1... Discriminator Loss: 0.7563... Generator Loss: 2.2231
Epoch 1/1... Discriminator Loss: 1.6258... Generator Loss: 0.6794
Epoch 1/1... Discriminator Loss: 1.3719... Generator Loss: 1.5973
Epoch 1/1... Discriminator Loss: 1.8683... Generator Loss: 0.2340
Epoch 1/1... Discriminator Loss: 0.6474... Generator Loss: 1.1325
Epoch 1/1... Discriminator Loss: 0.9274... Generator Loss: 1.0191
Epoch 1/1... Discriminator Loss: 1.3026... Generator Loss: 4.2769
Epoch 1/1... Discriminator Loss: 0.5292... Generator Loss: 1.3642
Epoch 1/1... Discriminator Loss: 0.9321... Generator Loss: 3.7559
Epoch 1/1... Discriminator Loss: 0.7115... Generator Loss: 0.9911
Epoch 1/1... Discriminator Loss: 0.5609... Generator Loss: 1.2986
Epoch 1/1... Discriminator Loss: 0.6965... Generator Loss: 2.1112
Epoch 1/1... Discriminator Loss: 0.2898... Generator Loss: 2.9118
Epoch 1/1... Discriminator Loss: 0.5486... Generator Loss: 1.4768
Epoch 1/1... Discriminator Loss: 0.5023... Generator Loss: 1.4291
Epoch 1/1... Discriminator Loss: 0.4350... Generator Loss: 2.0511
Epoch 1/1... Discriminator Loss: 1.1641... Generator Loss: 2.6308
Epoch 1/1... Discriminator Loss: 2.4285... Generator Loss: 3.9430
Epoch 1/1... Discriminator Loss: 0.8145... Generator Loss: 0.9632
Epoch 1/1... Discriminator Loss: 0.6910... Generator Loss: 1.9202
Epoch 1/1... Discriminator Loss: 0.4745... Generator Loss: 1.9086
Epoch 1/1... Discriminator Loss: 0.8870... Generator Loss: 2.1622
Epoch 1/1... Discriminator Loss: 0.9430... Generator Loss: 1.3876
Epoch 1/1... Discriminator Loss: 0.6881... Generator Loss: 1.7880
Epoch 1/1... Discriminator Loss: 1.0785... Generator Loss: 0.6215
Epoch 1/1... Discriminator Loss: 1.6908... Generator Loss: 0.2734
Epoch 1/1... Discriminator Loss: 0.6579... Generator Loss: 1.3659
Epoch 1/1... Discriminator Loss: 0.8449... Generator Loss: 0.6426
Epoch 1/1... Discriminator Loss: 0.7245... Generator Loss: 1.2423
Epoch 1/1... Discriminator Loss: 0.8618... Generator Loss: 1.0137
Epoch 1/1... Discriminator Loss: 0.9893... Generator Loss: 0.9038
Epoch 1/1... Discriminator Loss: 0.6628... Generator Loss: 2.4060
Epoch 1/1... Discriminator Loss: 1.3037... Generator Loss: 0.4825
Epoch 1/1... Discriminator Loss: 0.9941... Generator Loss: 0.6242
Epoch 1/1... Discriminator Loss: 0.8534... Generator Loss: 0.9375
Epoch 1/1... Discriminator Loss: 0.7702... Generator Loss: 2.3076
Epoch 1/1... Discriminator Loss: 1.1289... Generator Loss: 0.6283
Epoch 1/1... Discriminator Loss: 0.8273... Generator Loss: 0.9470
Epoch 1/1... Discriminator Loss: 0.7280... Generator Loss: 1.3100
Epoch 1/1... Discriminator Loss: 0.9091... Generator Loss: 1.0990
Epoch 1/1... Discriminator Loss: 0.7733... Generator Loss: 1.0130
Epoch 1/1... Discriminator Loss: 1.1597... Generator Loss: 0.6406
Epoch 1/1... Discriminator Loss: 1.0776... Generator Loss: 0.6472
Epoch 1/1... Discriminator Loss: 0.9299... Generator Loss: 0.7223
Epoch 1/1... Discriminator Loss: 1.6280... Generator Loss: 2.1790
Epoch 1/1... Discriminator Loss: 0.9728... Generator Loss: 0.8379
Epoch 1/1... Discriminator Loss: 0.7286... Generator Loss: 1.6896
Epoch 1/1... Discriminator Loss: 0.9545... Generator Loss: 0.6412
Epoch 1/1... Discriminator Loss: 0.9080... Generator Loss: 1.1739
Epoch 1/1... Discriminator Loss: 0.9369... Generator Loss: 1.1878
Epoch 1/1... Discriminator Loss: 0.9693... Generator Loss: 0.8348
Epoch 1/1... Discriminator Loss: 0.9854... Generator Loss: 1.1252
Epoch 1/1... Discriminator Loss: 0.9258... Generator Loss: 1.6743
Epoch 1/1... Discriminator Loss: 0.9682... Generator Loss: 0.8401
Epoch 1/1... Discriminator Loss: 1.2273... Generator Loss: 0.4928
Epoch 1/1... Discriminator Loss: 0.5703... Generator Loss: 1.6902
Epoch 1/1... Discriminator Loss: 1.2428... Generator Loss: 0.5330
Epoch 1/1... Discriminator Loss: 0.9509... Generator Loss: 0.9523
Epoch 1/1... Discriminator Loss: 0.9361... Generator Loss: 1.6018
Epoch 1/1... Discriminator Loss: 0.8034... Generator Loss: 0.7078
Epoch 1/1... Discriminator Loss: 0.9181... Generator Loss: 1.6539
Epoch 1/1... Discriminator Loss: 0.9231... Generator Loss: 0.9211
Epoch 1/1... Discriminator Loss: 0.8731... Generator Loss: 1.6402

提交项目

提交本项目前,确保运行所有 cells 后保存该文件。

保存该文件为 "dlnd_face_generation.ipynb", 并另存为 HTML 格式 "File" -> "Download as"。提交项目时请附带 "helper.py" 和 "problem_unittests.py" 文件。